1 /* 2 * Copyright (C) 1995-2004 Russell King 3 * 4 * Delay routines, using a pre-computed "loops_per_second" value. 5 */ 6 #ifndef __ASM_ARM_DELAY_H 7 #define __ASM_ARM_DELAY_H 8 9 #include <asm/memory.h> 10 #include <asm/param.h> /* HZ */ 11 12 #define MAX_UDELAY_MS 2 13 #define UDELAY_MULT ((UL(2199023) * HZ) >> 11) 14 #define UDELAY_SHIFT 30 15 16 #ifndef __ASSEMBLY__ 17 18 struct delay_timer { 19 unsigned long (*read_current_timer)(void); 20 unsigned long freq; 21 }; 22 23 extern struct arm_delay_ops { 24 void (*delay)(unsigned long); 25 void (*const_udelay)(unsigned long); 26 void (*udelay)(unsigned long); 27 } arm_delay_ops; 28 29 #define __delay(n) arm_delay_ops.delay(n) 30 31 /* 32 * This function intentionally does not exist; if you see references to 33 * it, it means that you're calling udelay() with an out of range value. 34 * 35 * With currently imposed limits, this means that we support a max delay 36 * of 2000us. Further limits: HZ<=1000 and bogomips<=3355 37 */ 38 extern void __bad_udelay(void); 39 40 /* 41 * division by multiplication: you don't have to worry about 42 * loss of precision. 43 * 44 * Use only for very small delays ( < 2 msec). Should probably use a 45 * lookup table, really, as the multiplications take much too long with 46 * short delays. This is a "reasonable" implementation, though (and the 47 * first constant multiplications gets optimized away if the delay is 48 * a constant) 49 */ 50 #define __udelay(n) arm_delay_ops.udelay(n) 51 #define __const_udelay(n) arm_delay_ops.const_udelay(n) 52 53 #define udelay(n) \ 54 (__builtin_constant_p(n) ? \ 55 ((n) > (MAX_UDELAY_MS * 1000) ? __bad_udelay() : \ 56 __const_udelay((n) * UDELAY_MULT)) : \ 57 __udelay(n)) 58 59 /* Loop-based definitions for assembly code. */ 60 extern void __loop_delay(unsigned long loops); 61 extern void __loop_udelay(unsigned long usecs); 62 extern void __loop_const_udelay(unsigned long); 63 64 /* Delay-loop timer registration. */ 65 #define ARCH_HAS_READ_CURRENT_TIMER 66 extern void register_current_timer_delay(const struct delay_timer *timer); 67 68 #endif /* __ASSEMBLY__ */ 69 70 #endif /* defined(_ARM_DELAY_H) */ 71 72